We can learn virtue even from the greatest sinner if we consider him as a teacher.
Commentary by Hazrat Inayat Khan:
There are many virtues, but there is one principal virtue. Every moment passed outside the presence of God is sin, and every moment in His presence is virtue. The whole object of the Sufi, after learning this way of communicating is to arrive at a stage where every moment of our life passes in communion with God, and where our every action is done as if God were before us. Is that within everyone's reach? We are meant to be so. Just think of a person who is in love: when he eats or drinks, whatever he does, the image of the beloved is there. In the same way, when the love of God has come, it is natural to think of God in everything we do.